Expiration Date for Excel Programs

Excel provides a robust development environment of which many people take full advantage. In fact, many people have written entire application programs using VBA with Excel as the framework.

If you do program development in Excel, you may be wondering if there is a way to write your program so that it will no longer work after a specific date. Fortunately, this is rather easy. One solution is to use something like the following as an Auto_Open macro:

Sub Auto_Open()
    Dim exdate As Date
    exdate = "11/30/2004"
    If Date > exdate Then
        MsgBox ("You have reached end of your trail period")
        ActiveWorkbook.Close
    End If	
    MsgBox ("You have " & exdate - Date & "Days left")
End Sub

If the date on the system running the program is greater than the date specified in the exdate variable, the user will see a message box indicating that their trial period has expired. When the user clicks on the OK button, the workbook closes. If the trial period is not over, then the message box indicates how many days are left in the period.

Of course, if you put a macro such as this in your application, it may stop you from opening the workbook to make program changes. The obvious way around this, of course, is to hold down the Shift key as you open the workbook. Doing so stops the Auto_Open macro from running. If your users know this, they can bypass the expiration check just as easily as you, however. The solution is to place similar checks within other macros that cannot be bypassed, and that are essential to your program.